In WO-2012/154116 (corresponding to US-2014/0088419) from the same applicant as the present application and incorporated as reference in its entirety herein, is a positioning marker known intended to be inserted into tissue, and which is applicable in relation to the marker loading assembly as disclosed in the present application.
When treating cancer tumours the physician is preparing the treatment e.g. by planning how large the dose of the medicine shall be or how much the radiation therapy shall comprise. Basis for the planning of the radiation therapy is done e.g. by using computer tomography images. These images are nowadays more and more frequently combined with images from other image generating devices such as magnetic camera images (a magnetic camera is normally referred to as MRI=magnetic resonance imaging) and images from a PET camera (PET=Positron Emission Tomography) in order to determine the extension of tumour in three dimensions, and also to determine the nature of the tumour.
In order to minimize the side effects on normal healthy tissue repeatedly radiation doses normally are given. During the imaging procedures it is important to carefully reposition the body and the tumour area according to predetermined parameters so the tumour area not will be missed.
Electronic image giving plates have been used for many years in order to control the position of the skeleton when using high energetic therapy beams on 4-20 megavolts (MV), which normally are used. In recent years the beam accelerators that give rise to the radiation doses have been equipped with complementary equipment resulting in x-ray beams in the kilovolt area (kV). These beams in the kV area have properties differentiated from the high energetic MV beam. The beams in the kV area are decelerated not only by the mass coming in its way, but also by a decelerating force in relation to the density of the material that the beams are passing by and the decelerating force is increasing almost exponentially with higher density.
Positioning markers are used in order to show the location of a tumour in a human or an animal tissue in order to accurately be able to identify the tumour when repeated images are obtained, and in particular when various imaging devices are used. These markers are decelerating the x-ray beams so much that the marker becomes visible on monitors where the results from different media are shown. Gold has a high density of 19.3 g/cm3, which makes it advantageously to be used as decelerating substance for the beams. Pure gold is also soft and possible to shape and is tolerated by the body as it is an inert material. The volume of gold may be limited so the substance becomes a thin wire, which also means that the marker may be inserted into the body by means of thin needles. Thereby the risk of bleedings and infections is minimized. Such a marker of gold is known by e.g. U.S. Pat. No. 8,406,054, which also is incorporated herein in its entirety.
Markers that are put into tissue of human or animal will rest mainly in the same place the entire life. Thus, it is extremely important that the markers not cause mechanical damage or give rise to allergies or other state of ill-health. The marker must have sufficient size and have an appropriate density in order for the marker to be clearly depicted at MR examination. The marker is an elongated object with a longitudinal axis and with a diameter of at the most 0.50 mm, e.g. 0.28 mm. The marker further has a predetermined total length, in the range of 5-30 mm, e.g. 10 mm or 20 mm. The marker comprises a plurality of first segments and a plurality of second segments, wherein the first and second segments are arranged alternately after each other. In one variation the marker comprises a first material, e.g. gold, with a density of at least 10 g/cm3, and this material constitute at least 90% by volume of the marker, and a second material, a ferromagnetic material, that is magnetic and that constitute at the most 10% by volume of the marker.
The positioning marker is inserted into tissue by an insertion needle, being a part of a medical insertion device, which is provided with an insertion needle having a distal end where the positioning marker is located prior insertion into the tissue.
When preparing the implantation of the marker it must be transferred from a loader needle provided with the marker to the distal end of the insertion needle. In some cases, not applicable when using a marker loading assembly disclosed herein, the marker may be inserted directly through the skin without transferring it to an insertion needle of a medical insertion device. The object of the marker loading assembly is to facilitate accurate and user-friendly transferring of the positioning marker to the insertion needle.